Change the behavior of password manager setting.
Currently password manager setting controls only saving behavior: when
it's on user is asked if credentials should be saved when it off save
prompt doesn't appear, but already saved credentials are still
filled.
This behavior is changed, so password manager setting is not only
controls saving of the credentials, but also filling, so that when
password manager setting is off credentials won't be filled.
BUG=517087
Review URL: https://codereview.chromium.org/
1314903011
Cr-Commit-Position: refs/heads/master@{#348872}